We report a study of the magnetic properties of a Mn12O12(O2CC4H3S)(16)(H2O)(4) single-molecule magnet. Polycrystalline powder samples were prepared by using a reaction of 3-thiophenecarboxylic acid with a slurry of Mn12O12(O2CCH3)(16)(H2O)(4) (noted as Mn-12-Ac) in methylene chloride. Magnetization measurements were performed down to 2 K with a magnetic field of up to 6 T. The magnetization curves showed a superparamagnetic behavior above the blocking temperature T-B and became hysteric below T-B due to the magnetic anisotropy of the molecule. The spin and the magnetic anisotropy constant of the molecule were determined by analyzing the magnetization data, and the results agree well with those for Mn-12-Ac. We also report the chemical deposition of a Mn12O12(O2CC4H3S)(16)(H2O)(4) film and an observation of its surface morphology by using scanning tunneling microscopy.